Manufacture of cardboard.



' air, particularly damp air,

WILLIAM GRANT 'FISKE, QF PURFLEET, ENGLAND.

MANUFACTURE OF CARDBOARD.

No Drawing.

To all "whom it may concern:

Be it known that I, WILLIAM GRANT FISKE. a citizen of the United Statesof America, and resident of Purflee-t, Essex, England, have invented acertain new and useful Improvement in and in the Manufacture ofCardboard, of which the following is a specification.

My invention has for its object the production of cardboard which shallpossess the quality of complete impermeability to but which, whilesufiiciently rigid to be self-supporting, shall yet be pliable to theextent necessary for permitting of its being bent without detriment toits capability of serving as a means of opposing the infiltration ofmoistureladen air; the improved cardboard being designed more especiallyto serve as a material for the manufacture of boxes or containers forgoods (such as tea, biscuits, etc.) which have hitherto required to beinclosed in tins in order that they may be effectually protected fromatmospheric influences.

The cardboard made in accordance with the present invention consists ofnot less than three distinct layers or thicknesses each of cardboard,together with intervening films or layers consisting solely of pitchadapted to serve not only as the non-hygroscopic air-excluding mediumbut also as the adhesive between the several card-layers. The improvedcardboard may thus be described as a triplex or multiplex pliableboardconstituted by a pile of alternate layers of card and pitch, theexternal layers being of card.

The improved cardboard may be made by drawing each internal layercontinuously through a container wherein the pitch is kept in a fluidstate by means of heat, so that a card-layer thus treated becomes coatedon both surfaces with a film of pitch, and on leaving the container,superposing the coated card-layers (if more than one) ,one upon anotherand at the same time applying the two external card-layers to theinternal card-layer or layers, the whole (2". e., the three or morecard-layers) being thereupon passed between a pair or pairs ofSpecification of Letters .Patent. Application filed March 18, 1912.Serial No. 68,614.

Patented July 23, 1912.

pressure-rollers whereby the several juxtaposed layers compr" to adhereclosely together while any excess of pitch is squeezed .out from betweenthe card-layers.

Especially in cold weather, it is desirable. either to co duct theoperation in a warm room or to subject the several layers of card to apreliminary heating so as to obviate the pitch becoming cooledtoo-rapidly by contact with the card material.

, From the above description'it is apparent that the substance employedto unite the three or more layers of fabric is one which shall besufficiently viscous and of a character that when spread in a thin layershall be practically impermeable by air and 'especlally damp air. Itmust, however, also be asubst-ance which will not either in itself, orby reason of incorporated oils'or other not strongly coherentingredients, tend to penetrate or permeate the card, it being theessence of this invention that the outer surfaces of the board shall beto all effects and purposes, card layers, having the usual or normalcard qualities, whereas interposed between them are one or more sheetsor layers of a viscous material impervious, when spread out into a thinlayer, to air, and having the property of not sinking deeply into orpenetrating the outer layers of the card, so that the board as'a wholewill be relatively air proof without yielding up its properties as aflexible, bendable cardboard suitable to be used as a container formerchandise. Pitch, of course, is an ideal material for this purpose,but it will be readily recognized that other substances having similarqualities would be the equivalent of pitch for the purposes of thisinvention.-

Claimed 1n the pile are caused The herein described improved cardboardpheric or thermal conditions, the said layers being pressed together sothat any excess ture, and also as the medium to prevent the is removedand the pitch appears therein as passage of moist air through thecardboard a very thin but uninterrupted film anchored as a whole,substantially as described. on both sides in the layers of the inclosinWILLIAM GRANT FISKE.

5 sheets but not penetratin said sheets, said 'Witnesses: I

film of pitch serving bot as the adhesive HAROLD JOHN PUT, to unite thelayers into single unitary struc- HARRY WILFRED QUINNELL.

